1. Field of the Invention
The invention relates to the field of preparation of surface-modified nano silicon dioxide materials from rice hulls.
2. Description of the Related Art
Conventional methods for producing nano silicon dioxide mainly include a precipitation method and a gas phase method. Primary raw materials used in such methods are from non-renewable resources, such as quartz and wollastonite, and the production process of the raw materials consumes large energy, causes serious pollution, and requires complex post-processing procedures. In addition, nano silicon dioxide prepared by such methods is usually hydrophilic, which cannot meet the current industrial requirements, so that it is necessary to conduct surface modification. At present, the modification method mainly utilizes appropriate chemical substance to react with hydroxyl radicals on the surface of the nano silicon dioxide to remove or decrease the amount of silanol groups on the surface and to transform the products from hydrophilicity into hydrophobicity. However, the modification method consumes a large amount of chemicals and involves complex processes, which increases the production costs.